/*
 * FXGL - JavaFX Game Library. The MIT License (MIT).
 * Copyright (c) AlmasB (almaslvl@gmail.com).
 * See LICENSE for details.
 */
package com.almasb.fxgl.physics.box2d.collision;

import com.almasb.fxgl.core.math.Vec2;
import com.almasb.fxgl.physics.box2d.collision.Distance.SimplexCache;
import com.almasb.fxgl.physics.box2d.collision.Manifold.ManifoldType;
import com.almasb.fxgl.physics.box2d.collision.shapes.CircleShape;
import com.almasb.fxgl.physics.box2d.collision.shapes.EdgeShape;
import com.almasb.fxgl.physics.box2d.collision.shapes.PolygonShape;
import com.almasb.fxgl.physics.box2d.collision.shapes.Shape;
import com.almasb.fxgl.physics.box2d.common.JBoxSettings;
import com.almasb.fxgl.physics.box2d.common.Rotation;
import com.almasb.fxgl.physics.box2d.common.Transform;
import com.almasb.fxgl.physics.box2d.pooling.IWorldPool;

/**
 * Functions used for computing contact points, distance queries, and TOI queries.
 * Collision methods are non-static for pooling speed, retrieve a collision object from the {@link IWorldPool}.
 * Should not be constructed.
 *
 * @author Daniel Murphy
 */
public final class Collision {

    private final IWorldPool pool;

    public Collision(IWorldPool pool) {
        incidentEdge[0] = new ClipVertex();
        incidentEdge[1] = new ClipVertex();
        clipPoints1[0] = new ClipVertex();
        clipPoints1[1] = new ClipVertex();
        clipPoints2[0] = new ClipVertex();
        clipPoints2[1] = new ClipVertex();
        this.pool = pool;
    }

    private final DistanceInput input = new DistanceInput();
    private final SimplexCache cache = new SimplexCache();
    private final DistanceOutput output = new DistanceOutput();

    /**
     * Determine if two generic shapes overlap.
     */
    public boolean testOverlap(Shape shapeA, int indexA,
                               Shape shapeB, int indexB,
                               Transform xfA, Transform xfB) {
        input.proxyA.set(shapeA, indexA);
        input.proxyB.set(shapeB, indexB);
        input.transformA.set(xfA);
        input.transformB.set(xfB);
        input.useRadii = true;

        cache.count = 0;

        pool.getDistance().distance(output, cache, input);
        // djm note: anything significant about 10.0f?
        return output.distance < 10.0f * JBoxSettings.EPSILON;
    }

    /**
     * Clipping for contact manifolds.
     * Sutherland-Hodgman clipping.
     */
    public static int clipSegmentToLine(ClipVertex[] vOut, ClipVertex[] vIn, Vec2 normal, float offset, int vertexIndexA) {

        // Start with no output points
        int numOut = 0;
        final ClipVertex vIn0 = vIn[0];
        final ClipVertex vIn1 = vIn[1];
        final Vec2 vIn0v = vIn0.v;
        final Vec2 vIn1v = vIn1.v;

        // Calculate the distance of end points to the line
        float distance0 = Vec2.dot(normal, vIn0v) - offset;
        float distance1 = Vec2.dot(normal, vIn1v) - offset;

        // If the points are behind the plane
        if (distance0 <= 0.0f) {
            vOut[numOut++].set(vIn0);
        }
        if (distance1 <= 0.0f) {
            vOut[numOut++].set(vIn1);
        }

        // If the points are on different sides of the plane
        if (distance0 * distance1 < 0.0f) {
            // Find intersection point of edge and plane
            float interp = distance0 / (distance0 - distance1);

            ClipVertex vOutNO = vOut[numOut];
            // vOut[numOut].v = vIn[0].v + interp * (vIn[1].v - vIn[0].v);
            vOutNO.v.x = vIn0v.x + interp * (vIn1v.x - vIn0v.x);
            vOutNO.v.y = vIn0v.y + interp * (vIn1v.y - vIn0v.y);

            // VertexA is hitting edgeB.
            vOutNO.id.indexA = (byte) vertexIndexA;
            vOutNO.id.indexB = vIn0.id.indexB;
            vOutNO.id.typeA = (byte) ContactID.Type.VERTEX.ordinal();
            vOutNO.id.typeB = (byte) ContactID.Type.FACE.ordinal();
            ++numOut;
        }

        return numOut;
    }

    // #### COLLISION STUFF (not from collision.h or collision.cpp) ####

    // djm pooling
    private static Vec2 d = new Vec2();

    /**
     * Compute the collision manifold between two circles.
     */
    @SuppressWarnings("PMD.UselessParentheses")
    public void collideCircles(Manifold manifold, CircleShape circle1, Transform xfA, CircleShape circle2, Transform xfB) {
        manifold.pointCount = 0;
        // before inline:
        // Transform.mulToOut(xfA, circle1.m_p, pA);
        // Transform.mulToOut(xfB, circle2.m_p, pB);
        // d.set(pB).subLocal(pA);
        // float distSqr = d.x * d.x + d.y * d.y;

        // after inline:
        Vec2 circle1p = circle1.center;
        Vec2 circle2p = circle2.center;
        float pAx = (xfA.q.c * circle1p.x - xfA.q.s * circle1p.y) + xfA.p.x;
        float pAy = (xfA.q.s * circle1p.x + xfA.q.c * circle1p.y) + xfA.p.y;
        float pBx = (xfB.q.c * circle2p.x - xfB.q.s * circle2p.y) + xfB.p.x;
        float pBy = (xfB.q.s * circle2p.x + xfB.q.c * circle2p.y) + xfB.p.y;
        float dx = pBx - pAx;
        float dy = pBy - pAy;
        float distSqr = dx * dx + dy * dy;
        // end inline

        final float radius = circle1.getRadius() + circle2.getRadius();
        if (distSqr > radius * radius) {
            return;
        }

        manifold.type = ManifoldType.CIRCLES;
        manifold.localPoint.set(circle1p);
        manifold.localNormal.setZero();
        manifold.pointCount = 1;

        manifold.points[0].localPoint.set(circle2p);
        manifold.points[0].id.zero();
    }

    /**
     * Compute the collision manifold between a polygon and a circle.
     *
     * @param manifold
     * @param polygon
     * @param xfA
     * @param circle
     * @param xfB
     */
    @SuppressWarnings("PMD.UselessParentheses")
    public void collidePolygonAndCircle(Manifold manifold,
                                        final PolygonShape polygon, final Transform xfA,
                                        final CircleShape circle, final Transform xfB) {
        manifold.pointCount = 0;
        // Vec2 v = circle.m_p;

        // Compute circle position in the frame of the polygon.
        // before inline:
        // Transform.mulToOutUnsafe(xfB, circle.m_p, c);
        // Transform.mulTransToOut(xfA, c, cLocal);
        // final float cLocalx = cLocal.x;
        // final float cLocaly = cLocal.y;
        // after inline:
        final Vec2 circlep = circle.center;
        final Rotation xfBq = xfB.q;
        final Rotation xfAq = xfA.q;
        final float cx = (xfBq.c * circlep.x - xfBq.s * circlep.y) + xfB.p.x;
        final float cy = (xfBq.s * circlep.x + xfBq.c * circlep.y) + xfB.p.y;
        final float px = cx - xfA.p.x;
        final float py = cy - xfA.p.y;
        final float cLocalx = (xfAq.c * px + xfAq.s * py);
        final float cLocaly = (-xfAq.s * px + xfAq.c * py);
        // end inline

        // Find the min separating edge.
        int normalIndex = 0;
        float separation = -Float.MAX_VALUE;
        final float radius = polygon.getRadius() + circle.getRadius();
        final int vertexCount = polygon.getVertexCount();
        float s;
        final Vec2[] vertices = polygon.m_vertices;
        final Vec2[] normals = polygon.m_normals;

        for (int i = 0; i < vertexCount; i++) {
            // before inline
            // temp.set(cLocal).subLocal(vertices[i]);
            // float s = Vec2.dot(normals[i], temp);
            // after inline
            final Vec2 vertex = vertices[i];
            final float tempx = cLocalx - vertex.x;
            final float tempy = cLocaly - vertex.y;
            s = normals[i].x * tempx + normals[i].y * tempy;


            if (s > radius) {
                // early out
                return;
            }

            if (s > separation) {
                separation = s;
                normalIndex = i;
            }
        }

        // Vertices that subtend the incident face.
        final int vertIndex1 = normalIndex;
        final int vertIndex2 = vertIndex1 + 1 < vertexCount ? vertIndex1 + 1 : 0;
        final Vec2 v1 = vertices[vertIndex1];
        final Vec2 v2 = vertices[vertIndex2];

        // If the center is inside the polygon ...
        if (separation < JBoxSettings.EPSILON) {
            manifold.pointCount = 1;
            manifold.type = ManifoldType.FACE_A;

            // before inline:
            // manifold.localNormal.set(normals[normalIndex]);
            // manifold.localPoint.set(v1).addLocal(v2).mulLocal(.5f);
            // manifold.points[0].localPoint.set(circle.m_p);
            // after inline:
            final Vec2 normal = normals[normalIndex];
            manifold.localNormal.x = normal.x;
            manifold.localNormal.y = normal.y;
            manifold.localPoint.x = (v1.x + v2.x) * .5f;
            manifold.localPoint.y = (v1.y + v2.y) * .5f;
            final ManifoldPoint mpoint = manifold.points[0];
            mpoint.localPoint.x = circlep.x;
            mpoint.localPoint.y = circlep.y;
            mpoint.id.zero();
            // end inline

            return;
        }

        // Compute barycentric coordinates
        // before inline:
        // temp.set(cLocal).subLocal(v1);
        // temp2.set(v2).subLocal(v1);
        // float u1 = Vec2.dot(temp, temp2);
        // temp.set(cLocal).subLocal(v2);
        // temp2.set(v1).subLocal(v2);
        // float u2 = Vec2.dot(temp, temp2);
        // after inline:
        final float tempX = cLocalx - v1.x;
        final float tempY = cLocaly - v1.y;
        final float temp2X = v2.x - v1.x;
        final float temp2Y = v2.y - v1.y;
        final float u1 = tempX * temp2X + tempY * temp2Y;

        final float temp3X = cLocalx - v2.x;
        final float temp3Y = cLocaly - v2.y;
        final float temp4X = v1.x - v2.x;
        final float temp4Y = v1.y - v2.y;
        final float u2 = temp3X * temp4X + temp3Y * temp4Y;
        // end inline

        if (u1 <= 0f) {
            // inlined
            final float dx = cLocalx - v1.x;
            final float dy = cLocaly - v1.y;
            if (dx * dx + dy * dy > radius * radius) {
                return;
            }

            manifold.pointCount = 1;
            manifold.type = ManifoldType.FACE_A;
            // before inline:
            // manifold.localNormal.set(cLocal).subLocal(v1);
            // after inline:
            manifold.localNormal.x = cLocalx - v1.x;
            manifold.localNormal.y = cLocaly - v1.y;
            // end inline
            manifold.localNormal.getLengthAndNormalize();
            manifold.localPoint.set(v1);
            manifold.points[0].localPoint.set(circlep);
            manifold.points[0].id.zero();
        } else if (u2 <= 0.0f) {
            // inlined
            final float dx = cLocalx - v2.x;
            final float dy = cLocaly - v2.y;
            if (dx * dx + dy * dy > radius * radius) {
                return;
            }

            manifold.pointCount = 1;
            manifold.type = ManifoldType.FACE_A;
            // before inline:
            // manifold.localNormal.set(cLocal).subLocal(v2);
            // after inline:
            manifold.localNormal.x = cLocalx - v2.x;
            manifold.localNormal.y = cLocaly - v2.y;
            // end inline
            manifold.localNormal.getLengthAndNormalize();
            manifold.localPoint.set(v2);
            manifold.points[0].localPoint.set(circlep);
            manifold.points[0].id.zero();
        } else {
            // Vec2 faceCenter = 0.5f * (v1 + v2);
            // (temp is faceCenter)
            // before inline:
            // temp.set(v1).addLocal(v2).mulLocal(.5f);
            //
            // temp2.set(cLocal).subLocal(temp);
            // separation = Vec2.dot(temp2, normals[vertIndex1]);
            // if (separation > radius) {
            // return;
            // }
            // after inline:
            final float fcx = (v1.x + v2.x) * .5f;
            final float fcy = (v1.y + v2.y) * .5f;

            final float tx = cLocalx - fcx;
            final float ty = cLocaly - fcy;
            final Vec2 normal = normals[vertIndex1];
            separation = tx * normal.x + ty * normal.y;
            if (separation > radius) {
                return;
            }
            // end inline

            manifold.pointCount = 1;
            manifold.type = ManifoldType.FACE_A;
            manifold.localNormal.set(normals[vertIndex1]);
            manifold.localPoint.x = fcx; // (faceCenter)
            manifold.localPoint.y = fcy;
            manifold.points[0].localPoint.set(circlep);
            manifold.points[0].id.zero();
        }
    }

    // djm pooling, and from above
    private final Vec2 temp = new Vec2();

    @SuppressWarnings("PMD.UselessParentheses")
    public void findIncidentEdge(final ClipVertex[] c,
                                 final PolygonShape poly1, final Transform xf1, int edge1,
                                 final PolygonShape poly2, final Transform xf2) {

        int count1 = poly1.getVertexCount();
        final Vec2[] normals1 = poly1.m_normals;

        int count2 = poly2.getVertexCount();
        final Vec2[] vertices2 = poly2.m_vertices;
        final Vec2[] normals2 = poly2.m_normals;

        assert 0 <= edge1 && edge1 < count1;

        final ClipVertex c0 = c[0];
        final ClipVertex c1 = c[1];
        final Rotation xf1q = xf1.q;
        final Rotation xf2q = xf2.q;

        // Get the normal of the reference edge in poly2's frame.
        // Vec2 normal1 = MulT(xf2.R, Mul(xf1.R, normals1[edge1]));
        // before inline:
        // Rot.mulToOutUnsafe(xf1.q, normals1[edge1], normal1); // temporary
        // Rot.mulTrans(xf2.q, normal1, normal1);
        // after inline:
        final Vec2 v = normals1[edge1];
        final float tempx = xf1q.c * v.x - xf1q.s * v.y;
        final float tempy = xf1q.s * v.x + xf1q.c * v.y;
        final float normal1x = xf2q.c * tempx + xf2q.s * tempy;
        final float normal1y = -xf2q.s * tempx + xf2q.c * tempy;

        // end inline

        // Find the incident edge on poly2.
        int index = 0;
        float minDot = Float.MAX_VALUE;
        for (int i = 0; i < count2; ++i) {
            Vec2 b = normals2[i];
            float dot = normal1x * b.x + normal1y * b.y;
            if (dot < minDot) {
                minDot = dot;
                index = i;
            }
        }

        // Build the clip vertices for the incident edge.
        int i1 = index;
        int i2 = i1 + 1 < count2 ? i1 + 1 : 0;

        // c0.v = Mul(xf2, vertices2[i1]);
        Vec2 v1 = vertices2[i1];
        Vec2 out = c0.v;
        out.x = (xf2q.c * v1.x - xf2q.s * v1.y) + xf2.p.x;
        out.y = (xf2q.s * v1.x + xf2q.c * v1.y) + xf2.p.y;
        c0.id.indexA = (byte) edge1;
        c0.id.indexB = (byte) i1;
        c0.id.typeA = (byte) ContactID.Type.FACE.ordinal();
        c0.id.typeB = (byte) ContactID.Type.VERTEX.ordinal();

        // c1.v = Mul(xf2, vertices2[i2]);
        Vec2 v2 = vertices2[i2];
        Vec2 out1 = c1.v;
        out1.x = (xf2q.c * v2.x - xf2q.s * v2.y) + xf2.p.x;
        out1.y = (xf2q.s * v2.x + xf2q.c * v2.y) + xf2.p.y;
        c1.id.indexA = (byte) edge1;
        c1.id.indexB = (byte) i2;
        c1.id.typeA = (byte) ContactID.Type.FACE.ordinal();
        c1.id.typeB = (byte) ContactID.Type.VERTEX.ordinal();
    }

    private final EdgeResults results1 = new EdgeResults();
    private final EdgeResults results2 = new EdgeResults();
    private final ClipVertex[] incidentEdge = new ClipVertex[2];
    private final Vec2 localTangent = new Vec2();
    private final Vec2 localNormal = new Vec2();
    private final Vec2 planePoint = new Vec2();
    private final Vec2 tangent = new Vec2();
    private final Vec2 v11 = new Vec2();
    private final Vec2 v12 = new Vec2();
    private final ClipVertex[] clipPoints1 = new ClipVertex[2];
    private final ClipVertex[] clipPoints2 = new ClipVertex[2];

    /**
     * Compute the collision manifold between two polygons.
     */
    @SuppressWarnings("PMD.UselessParentheses")
    public void collidePolygons(Manifold manifold,
                                final PolygonShape polyA, final Transform xfA,
                                final PolygonShape polyB, final Transform xfB) {
        // Find edge normal of max separation on A - return if separating axis is found
        // Find edge normal of max separation on B - return if separation axis is found
        // Choose reference edge as min(minA, minB)
        // Find incident edge
        // Clip

        // The normal points from 1 to 2

        manifold.pointCount = 0;
        float totalRadius = polyA.getRadius() + polyB.getRadius();

        findMaxSeparation(results1, polyA, xfA, polyB, xfB);
        if (results1.separation > totalRadius) {
            return;
        }

        findMaxSeparation(results2, polyB, xfB, polyA, xfA);
        if (results2.separation > totalRadius) {
            return;
        }

        final PolygonShape poly1;  // reference polygon
        final PolygonShape poly2;  // incident polygon
        Transform xf1, xf2;
        int edge1;                 // reference edge
        boolean flip;
        final float k_tol = 0.1f * JBoxSettings.linearSlop;

        if (results2.separation > results1.separation + k_tol) {
            poly1 = polyB;
            poly2 = polyA;
            xf1 = xfB;
            xf2 = xfA;
            edge1 = results2.edgeIndex;
            manifold.type = ManifoldType.FACE_B;
            flip = true;
        } else {
            poly1 = polyA;
            poly2 = polyB;
            xf1 = xfA;
            xf2 = xfB;
            edge1 = results1.edgeIndex;
            manifold.type = ManifoldType.FACE_A;
            flip = false;
        }
        final Rotation xf1q = xf1.q;

        findIncidentEdge(incidentEdge, poly1, xf1, edge1, poly2, xf2);

        int count1 = poly1.getVertexCount();
        final Vec2[] vertices1 = poly1.m_vertices;

        final int iv1 = edge1;
        final int iv2 = edge1 + 1 < count1 ? edge1 + 1 : 0;
        v11.set(vertices1[iv1]);
        v12.set(vertices1[iv2]);
        localTangent.x = v12.x - v11.x;
        localTangent.y = v12.y - v11.y;
        localTangent.getLengthAndNormalize();

        // Vec2 localNormal = Vec2.cross(dv, 1.0f);
        localNormal.x = 1f * localTangent.y;
        localNormal.y = -1f * localTangent.x;

        // Vec2 planePoint = 0.5f * (v11+ v12);
        planePoint.x = (v11.x + v12.x) * .5f;
        planePoint.y = (v11.y + v12.y) * .5f;

        // Rot.mulToOutUnsafe(xf1.q, localTangent, tangent);
        tangent.x = xf1q.c * localTangent.x - xf1q.s * localTangent.y;
        tangent.y = xf1q.s * localTangent.x + xf1q.c * localTangent.y;

        // Vec2.crossToOutUnsafe(tangent, 1f, normal);
        final float normalx = 1f * tangent.y;
        final float normaly = -1f * tangent.x;


        Transform.mulToOut(xf1, v11, v11);
        Transform.mulToOut(xf1, v12, v12);
        // v11 = Mul(xf1, v11);
        // v12 = Mul(xf1, v12);

        // Face offset
        // float frontOffset = Vec2.dot(normal, v11);
        float frontOffset = normalx * v11.x + normaly * v11.y;

        // Side offsets, extended by polytope skin thickness.
        // float sideOffset1 = -Vec2.dot(tangent, v11) + totalRadius;
        // float sideOffset2 = Vec2.dot(tangent, v12) + totalRadius;
        float sideOffset1 = -(tangent.x * v11.x + tangent.y * v11.y) + totalRadius;
        float sideOffset2 = tangent.x * v12.x + tangent.y * v12.y + totalRadius;

        // Clip incident edge against extruded edge1 side edges.
        // ClipVertex clipPoints1[2];
        // ClipVertex clipPoints2[2];
        int np;

        // Clip to box side 1
        // np = ClipSegmentToLine(clipPoints1, incidentEdge, -sideNormal, sideOffset1);
        tangent.negateLocal();
        np = clipSegmentToLine(clipPoints1, incidentEdge, tangent, sideOffset1, iv1);
        tangent.negateLocal();

        if (np < 2) {
            return;
        }

        // Clip to negative box side 1
        np = clipSegmentToLine(clipPoints2, clipPoints1, tangent, sideOffset2, iv2);

        if (np < 2) {
            return;
        }

        // Now clipPoints2 contains the clipped points.
        manifold.localNormal.set(localNormal);
        manifold.localPoint.set(planePoint);

        int pointCount = 0;
        for (int i = 0; i < JBoxSettings.maxManifoldPoints; ++i) {
            // float separation = Vec2.dot(normal, clipPoints2[i].v) - frontOffset;
            float separation = normalx * clipPoints2[i].v.x + normaly * clipPoints2[i].v.y - frontOffset;

            if (separation <= totalRadius) {
                ManifoldPoint cp = manifold.points[pointCount];
                // cp.m_localPoint = MulT(xf2, clipPoints2[i].v);
                Vec2 out = cp.localPoint;
                final float px = clipPoints2[i].v.x - xf2.p.x;
                final float py = clipPoints2[i].v.y - xf2.p.y;
                out.x = (xf2.q.c * px + xf2.q.s * py);
                out.y = (-xf2.q.s * px + xf2.q.c * py);
                cp.id.set(clipPoints2[i].id);
                if (flip) {
                    // Swap features
                    cp.id.flip();
                }
                ++pointCount;
            }
        }

        manifold.pointCount = pointCount;
    }

    private final Transform xf = new Transform();
    private final Vec2 n = new Vec2();
    private final Vec2 v1 = new Vec2();

    /**
     * Find the max separation between poly1 and poly2 using edge normals from poly1.
     */
    public void findMaxSeparation(EdgeResults results, PolygonShape poly1, Transform xf1, PolygonShape poly2, Transform xf2) {
        int count1 = poly1.getVertexCount();
        int count2 = poly2.getVertexCount();
        Vec2[] n1s = poly1.m_normals;
        Vec2[] v1s = poly1.m_vertices;
        Vec2[] v2s = poly2.m_vertices;

        Transform.mulTransToOutUnsafe(xf2, xf1, xf);
        final Rotation xfq = xf.q;

        int bestIndex = 0;
        float maxSeparation = -Float.MAX_VALUE;
        for (int i = 0; i < count1; i++) {
            // Get poly1 normal in frame2.
            Rotation.mulToOutUnsafe(xfq, n1s[i], n);
            Transform.mulToOutUnsafe(xf, v1s[i], v1);

            // Find deepest point for normal i.
            float si = Float.MAX_VALUE;
            for (int j = 0; j < count2; ++j) {
                Vec2 v2sj = v2s[j];
                float sij = n.x * (v2sj.x - v1.x) + n.y * (v2sj.y - v1.y);
                if (sij < si) {
                    si = sij;
                }
            }

            if (si > maxSeparation) {
                maxSeparation = si;
                bestIndex = i;
            }
        }

        results.edgeIndex = bestIndex;
        results.separation = maxSeparation;
    }

    private final Vec2 Q = new Vec2();
    private final Vec2 e = new Vec2();
    private final ContactID cf = new ContactID();
    private final Vec2 e1 = new Vec2();
    private final Vec2 P = new Vec2();

    // Compute contact points for edge versus circle.
    // This accounts for edge connectivity.
    public void collideEdgeAndCircle(Manifold manifold,
                                     final EdgeShape edgeA, final Transform xfA,
                                     final CircleShape circleB, final Transform xfB) {
        manifold.pointCount = 0;


        // Compute circle in frame of edge
        // Vec2 Q = MulT(xfA, Mul(xfB, circleB.m_p));
        Transform.mulToOutUnsafe(xfB, circleB.center, temp);
        Transform.mulTransToOutUnsafe(xfA, temp, Q);

        final Vec2 A = edgeA.m_vertex1;
        final Vec2 B = edgeA.m_vertex2;
        e.set(B).subLocal(A);

        // Barycentric coordinates
        float u = Vec2.dot(e, temp.set(B).subLocal(Q));
        float v = Vec2.dot(e, temp.set(Q).subLocal(A));

        float radius = edgeA.getRadius() + circleB.getRadius();

        // ContactFeature cf;
        cf.indexB = 0;
        cf.typeB = (byte) ContactID.Type.VERTEX.ordinal();

        // Region A
        if (v <= 0.0f) {
            final Vec2 P = A;
            d.set(Q).subLocal(P);
            float dd = Vec2.dot(d, d);
            if (dd > radius * radius) {
                return;
            }

            // Is there an edge connected to A?
            if (edgeA.m_hasVertex0) {
                final Vec2 A1 = edgeA.m_vertex0;
                final Vec2 B1 = A;
                e1.set(B1).subLocal(A1);
                float u1 = Vec2.dot(e1, temp.set(B1).subLocal(Q));

                // Is the circle in Region AB of the previous edge?
                if (u1 > 0.0f) {
                    return;
                }
            }

            cf.indexA = 0;
            cf.typeA = (byte) ContactID.Type.VERTEX.ordinal();
            manifold.pointCount = 1;
            manifold.type = Manifold.ManifoldType.CIRCLES;
            manifold.localNormal.setZero();
            manifold.localPoint.set(P);
            // manifold.points[0].id.key = 0;
            manifold.points[0].id.set(cf);
            manifold.points[0].localPoint.set(circleB.center);
            return;
        }

        // Region B
        if (u <= 0.0f) {
            Vec2 P = B;
            d.set(Q).subLocal(P);
            float dd = Vec2.dot(d, d);
            if (dd > radius * radius) {
                return;
            }

            // Is there an edge connected to B?
            if (edgeA.m_hasVertex3) {
                final Vec2 B2 = edgeA.m_vertex3;
                final Vec2 A2 = B;
                final Vec2 e2 = e1;
                e2.set(B2).subLocal(A2);
                float v2 = Vec2.dot(e2, temp.set(Q).subLocal(A2));

                // Is the circle in Region AB of the next edge?
                if (v2 > 0.0f) {
                    return;
                }
            }

            cf.indexA = 1;
            cf.typeA = (byte) ContactID.Type.VERTEX.ordinal();
            manifold.pointCount = 1;
            manifold.type = Manifold.ManifoldType.CIRCLES;
            manifold.localNormal.setZero();
            manifold.localPoint.set(P);
            // manifold.points[0].id.key = 0;
            manifold.points[0].id.set(cf);
            manifold.points[0].localPoint.set(circleB.center);
            return;
        }

        // Region AB
        float den = Vec2.dot(e, e);
        assert den > 0.0f;

        // Vec2 P = (1.0f / den) * (u * A + v * B);
        P.set(A).mulLocal(u).addLocal(temp.set(B).mulLocal(v));
        P.mulLocal(1.0f / den);
        d.set(Q).subLocal(P);
        float dd = Vec2.dot(d, d);
        if (dd > radius * radius) {
            return;
        }

        n.x = -e.y;
        n.y = e.x;
        if (Vec2.dot(n, temp.set(Q).subLocal(A)) < 0.0f) {
            n.set(-n.x, -n.y);
        }
        n.getLengthAndNormalize();

        cf.indexA = 0;
        cf.typeA = (byte) ContactID.Type.FACE.ordinal();
        manifold.pointCount = 1;
        manifold.type = Manifold.ManifoldType.FACE_A;
        manifold.localNormal.set(n);
        manifold.localPoint.set(A);
        // manifold.points[0].id.key = 0;
        manifold.points[0].id.set(cf);
        manifold.points[0].localPoint.set(circleB.center);
    }

    private final EPCollider collider = new EPCollider();

    public void collideEdgeAndPolygon(Manifold manifold,
                                      final EdgeShape edgeA, final Transform xfA,
                                      final PolygonShape polygonB, final Transform xfB) {
        collider.collide(manifold, edgeA, xfA, polygonB, xfB);
    }

    /**
     * Java-specific class for returning edge results
     */
    private static class EdgeResults {
        float separation;
        int edgeIndex;
    }

    /**
     * Used for computing contact manifolds.
     */
    public static class ClipVertex {
        public final Vec2 v;
        public final ContactID id;

        public ClipVertex() {
            v = new Vec2();
            id = new ContactID();
        }

        public void set(final ClipVertex cv) {
            Vec2 v1 = cv.v;
            v.x = v1.x;
            v.y = v1.y;
            ContactID c = cv.id;
            id.indexA = c.indexA;
            id.indexB = c.indexB;
            id.typeA = c.typeA;
            id.typeB = c.typeB;
        }
    }

    /**
     * This structure is used to keep track of the best separating axis.
     */
    private static class EPAxis {
        enum Type {
            UNKNOWN, EDGE_A, EDGE_B
        }

        Type type;
        int index;
        float separation;
    }

    /**
     * This holds polygon B expressed in frame A.
     */
    private static class TempPolygon {
        final Vec2[] vertices = new Vec2[JBoxSettings.maxPolygonVertices];
        final Vec2[] normals = new Vec2[JBoxSettings.maxPolygonVertices];
        int count;

        TempPolygon() {
            for (int i = 0; i < vertices.length; i++) {
                vertices[i] = new Vec2();
                normals[i] = new Vec2();
            }
        }
    }

    /**
     * Reference face used for clipping
     */
    private static class ReferenceFace {
        int i1, i2;
        final Vec2 v1 = new Vec2();
        final Vec2 v2 = new Vec2();
        final Vec2 normal = new Vec2();

        final Vec2 sideNormal1 = new Vec2();
        float sideOffset1;

        final Vec2 sideNormal2 = new Vec2();
        float sideOffset2;
    }

    /**
     * This class collides and edge and a polygon, taking into account edge adjacency.
     */
    private static class EPCollider {

        final TempPolygon m_polygonB = new TempPolygon();

        final Transform m_xf = new Transform();
        final Vec2 m_centroidB = new Vec2();
        Vec2 m_v0 = new Vec2();
        Vec2 m_v1 = new Vec2();
        Vec2 m_v2 = new Vec2();
        Vec2 m_v3 = new Vec2();
        final Vec2 m_normal0 = new Vec2();
        final Vec2 m_normal1 = new Vec2();
        final Vec2 m_normal2 = new Vec2();
        final Vec2 m_normal = new Vec2();

        final Vec2 m_lowerLimit = new Vec2();
        final Vec2 m_upperLimit = new Vec2();
        float m_radius;
        boolean m_front;

        EPCollider() {
            for (int i = 0; i < 2; i++) {
                ie[i] = new ClipVertex();
                clipPoints1[i] = new ClipVertex();
                clipPoints2[i] = new ClipVertex();
            }
        }

        private final Vec2 edge1 = new Vec2();
        private final Vec2 temp = new Vec2();
        private final Vec2 edge0 = new Vec2();
        private final Vec2 edge2 = new Vec2();
        private final ClipVertex[] ie = new ClipVertex[2];
        private final ClipVertex[] clipPoints1 = new ClipVertex[2];
        private final ClipVertex[] clipPoints2 = new ClipVertex[2];
        private final ReferenceFace rf = new ReferenceFace();
        private final EPAxis edgeAxis = new EPAxis();
        private final EPAxis polygonAxis = new EPAxis();

        public void collide(Manifold manifold, final EdgeShape edgeA, final Transform xfA,
                            final PolygonShape polygonB, final Transform xfB) {

            Transform.mulTransToOutUnsafe(xfA, xfB, m_xf);
            Transform.mulToOutUnsafe(m_xf, polygonB.m_centroid, m_centroidB);

            m_v0 = edgeA.m_vertex0;
            m_v1 = edgeA.m_vertex1;
            m_v2 = edgeA.m_vertex2;
            m_v3 = edgeA.m_vertex3;

            boolean hasVertex0 = edgeA.m_hasVertex0;
            boolean hasVertex3 = edgeA.m_hasVertex3;

            edge1.set(m_v2).subLocal(m_v1);
            edge1.getLengthAndNormalize();
            m_normal1.set(edge1.y, -edge1.x);
            float offset1 = Vec2.dot(m_normal1, temp.set(m_centroidB).subLocal(m_v1));
            float offset0 = 0.0f, offset2 = 0.0f;
            boolean convex1 = false, convex2 = false;

            // Is there a preceding edge?
            if (hasVertex0) {
                edge0.set(m_v1).subLocal(m_v0);
                edge0.getLengthAndNormalize();
                m_normal0.set(edge0.y, -edge0.x);
                convex1 = Vec2.cross(edge0, edge1) >= 0.0f;
                offset0 = Vec2.dot(m_normal0, temp.set(m_centroidB).subLocal(m_v0));
            }

            // Is there a following edge?
            if (hasVertex3) {
                edge2.set(m_v3).subLocal(m_v2);
                edge2.getLengthAndNormalize();
                m_normal2.set(edge2.y, -edge2.x);
                convex2 = Vec2.cross(edge1, edge2) > 0.0f;
                offset2 = Vec2.dot(m_normal2, temp.set(m_centroidB).subLocal(m_v2));
            }

            // Determine front or back collision. Determine collision normal limits.
            if (hasVertex0 && hasVertex3) {
                if (convex1 && convex2) {
                    m_front = offset0 >= 0.0f || offset1 >= 0.0f || offset2 >= 0.0f;
                    if (m_front) {
                        m_normal.x = m_normal1.x;
                        m_normal.y = m_normal1.y;
                        m_lowerLimit.x = m_normal0.x;
                        m_lowerLimit.y = m_normal0.y;
                        m_upperLimit.x = m_normal2.x;
                        m_upperLimit.y = m_normal2.y;
                    } else {
                        m_normal.x = -m_normal1.x;
                        m_normal.y = -m_normal1.y;
                        m_lowerLimit.x = -m_normal1.x;
                        m_lowerLimit.y = -m_normal1.y;
                        m_upperLimit.x = -m_normal1.x;
                        m_upperLimit.y = -m_normal1.y;
                    }
                } else if (convex1) {
                    m_front = offset0 >= 0.0f || offset1 >= 0.0f && offset2 >= 0.0f;
                    if (m_front) {
                        m_normal.x = m_normal1.x;
                        m_normal.y = m_normal1.y;
                        m_lowerLimit.x = m_normal0.x;
                        m_lowerLimit.y = m_normal0.y;
                        m_upperLimit.x = m_normal1.x;
                        m_upperLimit.y = m_normal1.y;
                    } else {
                        m_normal.x = -m_normal1.x;
                        m_normal.y = -m_normal1.y;
                        m_lowerLimit.x = -m_normal2.x;
                        m_lowerLimit.y = -m_normal2.y;
                        m_upperLimit.x = -m_normal1.x;
                        m_upperLimit.y = -m_normal1.y;
                    }
                } else if (convex2) {
                    m_front = offset2 >= 0.0f || offset0 >= 0.0f && offset1 >= 0.0f;
                    if (m_front) {
                        m_normal.x = m_normal1.x;
                        m_normal.y = m_normal1.y;
                        m_lowerLimit.x = m_normal1.x;
                        m_lowerLimit.y = m_normal1.y;
                        m_upperLimit.x = m_normal2.x;
                        m_upperLimit.y = m_normal2.y;
                    } else {
                        m_normal.x = -m_normal1.x;
                        m_normal.y = -m_normal1.y;
                        m_lowerLimit.x = -m_normal1.x;
                        m_lowerLimit.y = -m_normal1.y;
                        m_upperLimit.x = -m_normal0.x;
                        m_upperLimit.y = -m_normal0.y;
                    }
                } else {
                    m_front = offset0 >= 0.0f && offset1 >= 0.0f && offset2 >= 0.0f;
                    if (m_front) {
                        m_normal.x = m_normal1.x;
                        m_normal.y = m_normal1.y;
                        m_lowerLimit.x = m_normal1.x;
                        m_lowerLimit.y = m_normal1.y;
                        m_upperLimit.x = m_normal1.x;
                        m_upperLimit.y = m_normal1.y;
                    } else {
                        m_normal.x = -m_normal1.x;
                        m_normal.y = -m_normal1.y;
                        m_lowerLimit.x = -m_normal2.x;
                        m_lowerLimit.y = -m_normal2.y;
                        m_upperLimit.x = -m_normal0.x;
                        m_upperLimit.y = -m_normal0.y;
                    }
                }
            } else if (hasVertex0) {
                if (convex1) {
                    m_front = offset0 >= 0.0f || offset1 >= 0.0f;
                    if (m_front) {
                        m_normal.x = m_normal1.x;
                        m_normal.y = m_normal1.y;
                        m_lowerLimit.x = m_normal0.x;
                        m_lowerLimit.y = m_normal0.y;
                        m_upperLimit.x = -m_normal1.x;
                        m_upperLimit.y = -m_normal1.y;
                    } else {
                        m_normal.x = -m_normal1.x;
                        m_normal.y = -m_normal1.y;
                        m_lowerLimit.x = m_normal1.x;
                        m_lowerLimit.y = m_normal1.y;
                        m_upperLimit.x = -m_normal1.x;
                        m_upperLimit.y = -m_normal1.y;
                    }
                } else {
                    m_front = offset0 >= 0.0f && offset1 >= 0.0f;
                    if (m_front) {
                        m_normal.x = m_normal1.x;
                        m_normal.y = m_normal1.y;
                        m_lowerLimit.x = m_normal1.x;
                        m_lowerLimit.y = m_normal1.y;
                        m_upperLimit.x = -m_normal1.x;
                        m_upperLimit.y = -m_normal1.y;
                    } else {
                        m_normal.x = -m_normal1.x;
                        m_normal.y = -m_normal1.y;
                        m_lowerLimit.x = m_normal1.x;
                        m_lowerLimit.y = m_normal1.y;
                        m_upperLimit.x = -m_normal0.x;
                        m_upperLimit.y = -m_normal0.y;
                    }
                }
            } else if (hasVertex3) {
                if (convex2) {
                    m_front = offset1 >= 0.0f || offset2 >= 0.0f;
                    if (m_front) {
                        m_normal.x = m_normal1.x;
                        m_normal.y = m_normal1.y;
                        m_lowerLimit.x = -m_normal1.x;
                        m_lowerLimit.y = -m_normal1.y;
                        m_upperLimit.x = m_normal2.x;
                        m_upperLimit.y = m_normal2.y;
                    } else {
                        m_normal.x = -m_normal1.x;
                        m_normal.y = -m_normal1.y;
                        m_lowerLimit.x = -m_normal1.x;
                        m_lowerLimit.y = -m_normal1.y;
                        m_upperLimit.x = m_normal1.x;
                        m_upperLimit.y = m_normal1.y;
                    }
                } else {
                    m_front = offset1 >= 0.0f && offset2 >= 0.0f;
                    if (m_front) {
                        m_normal.x = m_normal1.x;
                        m_normal.y = m_normal1.y;
                        m_lowerLimit.x = -m_normal1.x;
                        m_lowerLimit.y = -m_normal1.y;
                        m_upperLimit.x = m_normal1.x;
                        m_upperLimit.y = m_normal1.y;
                    } else {
                        m_normal.x = -m_normal1.x;
                        m_normal.y = -m_normal1.y;
                        m_lowerLimit.x = -m_normal2.x;
                        m_lowerLimit.y = -m_normal2.y;
                        m_upperLimit.x = m_normal1.x;
                        m_upperLimit.y = m_normal1.y;
                    }
                }
            } else {
                m_front = offset1 >= 0.0f;
                if (m_front) {
                    m_normal.x = m_normal1.x;
                    m_normal.y = m_normal1.y;
                    m_lowerLimit.x = -m_normal1.x;
                    m_lowerLimit.y = -m_normal1.y;
                    m_upperLimit.x = -m_normal1.x;
                    m_upperLimit.y = -m_normal1.y;
                } else {
                    m_normal.x = -m_normal1.x;
                    m_normal.y = -m_normal1.y;
                    m_lowerLimit.x = m_normal1.x;
                    m_lowerLimit.y = m_normal1.y;
                    m_upperLimit.x = m_normal1.x;
                    m_upperLimit.y = m_normal1.y;
                }
            }

            // Get polygonB in frameA
            m_polygonB.count = polygonB.getVertexCount();
            for (int i = 0; i < polygonB.getVertexCount(); ++i) {
                Transform.mulToOutUnsafe(m_xf, polygonB.m_vertices[i], m_polygonB.vertices[i]);
                Rotation.mulToOutUnsafe(m_xf.q, polygonB.m_normals[i], m_polygonB.normals[i]);
            }

            m_radius = 2.0f * JBoxSettings.polygonRadius;

            manifold.pointCount = 0;

            computeEdgeSeparation(edgeAxis);

            // If no valid normal can be found than this edge should not collide.
            if (edgeAxis.type == EPAxis.Type.UNKNOWN) {
                return;
            }

            if (edgeAxis.separation > m_radius) {
                return;
            }

            computePolygonSeparation(polygonAxis);
            if (polygonAxis.type != EPAxis.Type.UNKNOWN && polygonAxis.separation > m_radius) {
                return;
            }

            // Use hysteresis for jitter reduction.
            final float k_relativeTol = 0.98f;
            final float k_absoluteTol = 0.001f;

            EPAxis primaryAxis;
            if (polygonAxis.type == EPAxis.Type.UNKNOWN) {
                primaryAxis = edgeAxis;
            } else if (polygonAxis.separation > k_relativeTol * edgeAxis.separation + k_absoluteTol) {
                primaryAxis = polygonAxis;
            } else {
                primaryAxis = edgeAxis;
            }

            final ClipVertex ie0 = ie[0];
            final ClipVertex ie1 = ie[1];

            if (primaryAxis.type == EPAxis.Type.EDGE_A) {
                manifold.type = Manifold.ManifoldType.FACE_A;

                // Search for the polygon normal that is most anti-parallel to the edge normal.
                int bestIndex = 0;
                float bestValue = Vec2.dot(m_normal, m_polygonB.normals[0]);
                for (int i = 1; i < m_polygonB.count; ++i) {
                    float value = Vec2.dot(m_normal, m_polygonB.normals[i]);
                    if (value < bestValue) {
                        bestValue = value;
                        bestIndex = i;
                    }
                }

                int i1 = bestIndex;
                int i2 = i1 + 1 < m_polygonB.count ? i1 + 1 : 0;

                ie0.v.set(m_polygonB.vertices[i1]);
                ie0.id.indexA = 0;
                ie0.id.indexB = (byte) i1;
                ie0.id.typeA = (byte) ContactID.Type.FACE.ordinal();
                ie0.id.typeB = (byte) ContactID.Type.VERTEX.ordinal();

                ie1.v.set(m_polygonB.vertices[i2]);
                ie1.id.indexA = 0;
                ie1.id.indexB = (byte) i2;
                ie1.id.typeA = (byte) ContactID.Type.FACE.ordinal();
                ie1.id.typeB = (byte) ContactID.Type.VERTEX.ordinal();

                if (m_front) {
                    rf.i1 = 0;
                    rf.i2 = 1;
                    rf.v1.set(m_v1);
                    rf.v2.set(m_v2);
                    rf.normal.set(m_normal1);
                } else {
                    rf.i1 = 1;
                    rf.i2 = 0;
                    rf.v1.set(m_v2);
                    rf.v2.set(m_v1);
                    rf.normal.set(m_normal1).negateLocal();
                }
            } else {
                manifold.type = Manifold.ManifoldType.FACE_B;

                ie0.v.set(m_v1);
                ie0.id.indexA = 0;
                ie0.id.indexB = (byte) primaryAxis.index;
                ie0.id.typeA = (byte) ContactID.Type.VERTEX.ordinal();
                ie0.id.typeB = (byte) ContactID.Type.FACE.ordinal();

                ie1.v.set(m_v2);
                ie1.id.indexA = 0;
                ie1.id.indexB = (byte) primaryAxis.index;
                ie1.id.typeA = (byte) ContactID.Type.VERTEX.ordinal();
                ie1.id.typeB = (byte) ContactID.Type.FACE.ordinal();

                rf.i1 = primaryAxis.index;
                rf.i2 = rf.i1 + 1 < m_polygonB.count ? rf.i1 + 1 : 0;
                rf.v1.set(m_polygonB.vertices[rf.i1]);
                rf.v2.set(m_polygonB.vertices[rf.i2]);
                rf.normal.set(m_polygonB.normals[rf.i1]);
            }

            rf.sideNormal1.set(rf.normal.y, -rf.normal.x);
            rf.sideNormal2.set(rf.sideNormal1).negateLocal();
            rf.sideOffset1 = Vec2.dot(rf.sideNormal1, rf.v1);
            rf.sideOffset2 = Vec2.dot(rf.sideNormal2, rf.v2);

            // Clip incident edge against extruded edge1 side edges.
            int np;

            // Clip to box side 1
            np = clipSegmentToLine(clipPoints1, ie, rf.sideNormal1, rf.sideOffset1, rf.i1);

            if (np < JBoxSettings.maxManifoldPoints) {
                return;
            }

            // Clip to negative box side 1
            np = clipSegmentToLine(clipPoints2, clipPoints1, rf.sideNormal2, rf.sideOffset2, rf.i2);

            if (np < JBoxSettings.maxManifoldPoints) {
                return;
            }

            // Now clipPoints2 contains the clipped points.
            if (primaryAxis.type == EPAxis.Type.EDGE_A) {
                manifold.localNormal.set(rf.normal);
                manifold.localPoint.set(rf.v1);
            } else {
                manifold.localNormal.set(polygonB.m_normals[rf.i1]);
                manifold.localPoint.set(polygonB.m_vertices[rf.i1]);
            }

            int pointCount = 0;
            for (int i = 0; i < JBoxSettings.maxManifoldPoints; ++i) {
                float separation;

                separation = Vec2.dot(rf.normal, temp.set(clipPoints2[i].v).subLocal(rf.v1));

                if (separation <= m_radius) {
                    ManifoldPoint cp = manifold.points[pointCount];

                    if (primaryAxis.type == EPAxis.Type.EDGE_A) {
                        // cp.localPoint = MulT(m_xf, clipPoints2[i].v);
                        Transform.mulTransToOutUnsafe(m_xf, clipPoints2[i].v, cp.localPoint);
                        cp.id.set(clipPoints2[i].id);
                    } else {
                        cp.localPoint.set(clipPoints2[i].v);
                        cp.id.typeA = clipPoints2[i].id.typeB;
                        cp.id.typeB = clipPoints2[i].id.typeA;
                        cp.id.indexA = clipPoints2[i].id.indexB;
                        cp.id.indexB = clipPoints2[i].id.indexA;
                    }

                    ++pointCount;
                }
            }

            manifold.pointCount = pointCount;
        }

        public void computeEdgeSeparation(EPAxis axis) {
            axis.type = EPAxis.Type.EDGE_A;
            axis.index = m_front ? 0 : 1;
            axis.separation = Float.MAX_VALUE;
            float nx = m_normal.x;
            float ny = m_normal.y;

            for (int i = 0; i < m_polygonB.count; ++i) {
                Vec2 v = m_polygonB.vertices[i];
                float tempx = v.x - m_v1.x;
                float tempy = v.y - m_v1.y;
                float s = nx * tempx + ny * tempy;
                if (s < axis.separation) {
                    axis.separation = s;
                }
            }
        }

        private final Vec2 perp = new Vec2();
        private final Vec2 n = new Vec2();

        public void computePolygonSeparation(EPAxis axis) {
            axis.type = EPAxis.Type.UNKNOWN;
            axis.index = -1;
            axis.separation = -Float.MAX_VALUE;

            perp.x = -m_normal.y;
            perp.y = m_normal.x;

            for (int i = 0; i < m_polygonB.count; ++i) {
                Vec2 normalB = m_polygonB.normals[i];
                Vec2 vB = m_polygonB.vertices[i];
                n.x = -normalB.x;
                n.y = -normalB.y;

                // float s1 = Vec2.dot(n, temp.set(vB).subLocal(m_v1));
                // float s2 = Vec2.dot(n, temp.set(vB).subLocal(m_v2));
                float tempx = vB.x - m_v1.x;
                float tempy = vB.y - m_v1.y;
                float s1 = n.x * tempx + n.y * tempy;
                tempx = vB.x - m_v2.x;
                tempy = vB.y - m_v2.y;
                float s2 = n.x * tempx + n.y * tempy;
                float s = Math.min(s1, s2);

                if (s > m_radius) {
                    // No collision
                    axis.type = EPAxis.Type.EDGE_B;
                    axis.index = i;
                    axis.separation = s;
                    return;
                }

                // Adjacency
                if (n.x * perp.x + n.y * perp.y >= 0.0f) {
                    if (Vec2.dot(temp.set(n).subLocal(m_upperLimit), m_normal) < -JBoxSettings.angularSlop) {
                        continue;
                    }
                } else {
                    if (Vec2.dot(temp.set(n).subLocal(m_lowerLimit), m_normal) < -JBoxSettings.angularSlop) {
                        continue;
                    }
                }

                if (s > axis.separation) {
                    axis.type = EPAxis.Type.EDGE_B;
                    axis.index = i;
                    axis.separation = s;
                }
            }
        }
    }
}
